Question

Find the value of $x$ So that the given four numbers are in proportion:
(i) $x,6,10\text{and}15$.

Answer 1

Since the numbers $x,6,10\text{and}15$ are in proportion then ,

$\Rightarrow$ $x:6=10:15$

$\Rightarrow$ $\frac{x}{6}=\frac{10}{15}$

$\Rightarrow$ $x\times 15=10\times 6$

($\because$ $\text{Product of extremes = Product of means}$)

$\Rightarrow$ $x=\frac{10\times 6}{15}=\frac{(5\times 2)\times (3\times 2)}{5\times 3}=2\times 2$

$\therefore$ $x=4$

Hence , the value of $x$ is $4$.